gdb/python/py-cmd.c

   1 /* gdb commands implemented in Python
   2
   3    Copyright (C) 2008-2017 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20
  21 #include "defs.h"
  22 #include "arch-utils.h"
  23 #include "value.h"
  24 #include "python-internal.h"
  25 #include "charset.h"
  26 #include "gdbcmd.h"
  27 #include "cli/cli-decode.h"
  28 #include "completer.h"
  29 #include "language.h"
  30 #include "py-ref.h"
  31
  32 /* Struct representing built-in completion types.  */
  33 struct cmdpy_completer
  34 {
  35   /* Python symbol name.  */
  36   const char *name;
  37   /* Completion function.  */
  38   completer_ftype *completer;
  39 };
  40
  41 static const struct cmdpy_completer completers[] =
  42 {
  43   { "COMPLETE_NONE", noop_completer },
  44   { "COMPLETE_FILENAME", filename_completer },
  45   { "COMPLETE_LOCATION", location_completer },
  46   { "COMPLETE_COMMAND", command_completer },
  47   { "COMPLETE_SYMBOL", symbol_completer },
  48   { "COMPLETE_EXPRESSION", expression_completer },
  49 };
  50
  51 #define N_COMPLETERS (sizeof (completers) / sizeof (completers[0]))
  52
  53 /* A gdb command.  For the time being only ordinary commands (not
  54    set/show commands) are allowed.  */
  55 struct cmdpy_object
  56 {
  57   PyObject_HEAD
  58
  59   /* The corresponding gdb command object, or NULL if the command is
  60      no longer installed.  */
  61   struct cmd_list_element *command;
  62
  63   /* A prefix command requires storage for a list of its sub-commands.
  64      A pointer to this is passed to add_prefix_command, and to add_cmd
  65      for sub-commands of that prefix.  If this Command is not a prefix
  66      command, then this field is unused.  */
  67   struct cmd_list_element *sub_list;
  68 };
  69
  70 typedef struct cmdpy_object cmdpy_object;
  71
  72 extern PyTypeObject cmdpy_object_type
  73     CPYCHECKER_TYPE_OBJECT_FOR_TYPEDEF ("cmdpy_object");
  74
  75 /* Constants used by this module.  */
  76 static PyObject *invoke_cst;
  77 static PyObject *complete_cst;
  78
  79 \f
  80
  81 /* Python function which wraps dont_repeat.  */
  82 static PyObject *
  83 cmdpy_dont_repeat (PyObject *self, PyObject *args)
  84 {
  85   dont_repeat ();
  86   Py_RETURN_NONE;
  87 }
  88
  89 \f
  90
  91 /* Called if the gdb cmd_list_element is destroyed.  */
  92
  93 static void
  94 cmdpy_destroyer (struct cmd_list_element *self, void *context)
  95 {
  96   gdbpy_enter enter_py (get_current_arch (), current_language);
  97
  98   /* Release our hold on the command object.  */
  99   gdbpy_ref<cmdpy_object> cmd ((cmdpy_object *) context);
 100   cmd->command = NULL;
 101
 102   /* We allocated the name, doc string, and perhaps the prefix
 103      name.  */
 104   xfree ((char *) self->name);
 105   xfree ((char *) self->doc);
 106   xfree ((char *) self->prefixname);
 107 }
 108
 109 /* Called by gdb to invoke the command.  */
 110
 111 static void
 112 cmdpy_function (struct cmd_list_element *command,
 113                 char *args_entry, int from_tty)
 114 {
 115   const char *args = args_entry;
 116   cmdpy_object *obj = (cmdpy_object *) get_cmd_context (command);
 117
 118   gdbpy_enter enter_py (get_current_arch (), current_language);
 119
 120   if (! obj)
 121     error (_("Invalid invocation of Python command object."));
 122   if (! PyObject_HasAttr ((PyObject *) obj, invoke_cst))
 123     {
 124       if (obj->command->prefixname)
 125         {
 126           /* A prefix command does not need an invoke method.  */
 127           return;
 128         }
 129       error (_("Python command object missing 'invoke' method."));
 130     }
 131
 132   if (! args)
 133     args = "";
 134   gdbpy_ref<> argobj (PyUnicode_Decode (args, strlen (args), host_charset (),
 135                                         NULL));
 136   if (argobj == NULL)
 137     {
 138       gdbpy_print_stack ();
 139       error (_("Could not convert arguments to Python string."));
 140     }
 141
 142   gdbpy_ref<> ttyobj (from_tty ? Py_True : Py_False);
 143   Py_INCREF (ttyobj.get ());
 144   gdbpy_ref<> result (PyObject_CallMethodObjArgs ((PyObject *) obj, invoke_cst,
 145                                                   argobj.get (), ttyobj.get (),
 146                                                   NULL));
 147
 148   if (result == NULL)
 149     {
 150       PyObject *ptype, *pvalue, *ptraceback;
 151
 152       PyErr_Fetch (&ptype, &pvalue, &ptraceback);
 153
 154       /* Try to fetch an error message contained within ptype, pvalue.
 155          When fetching the error message we need to make our own copy,
 156          we no longer own ptype, pvalue after the call to PyErr_Restore.  */
 157
 158       gdb::unique_xmalloc_ptr<char>
 159         msg (gdbpy_exception_to_string (ptype, pvalue));
 160
 161       if (msg == NULL)
 162         {
 163           /* An error occurred computing the string representation of the
 164              error message.  This is rare, but we should inform the user.  */
 165           printf_filtered (_("An error occurred in a Python command\n"
 166                              "and then another occurred computing the "
 167                              "error message.\n"));
 168           gdbpy_print_stack ();
 169         }
 170
 171       /* Don't print the stack for gdb.GdbError exceptions.
 172          It is generally used to flag user errors.
 173
 174          We also don't want to print "Error occurred in Python command"
 175          for user errors.  However, a missing message for gdb.GdbError
 176          exceptions is arguably a bug, so we flag it as such.  */
 177
 178       if (! PyErr_GivenExceptionMatches (ptype, gdbpy_gdberror_exc)
 179           || msg == NULL || *msg == '\0')
 180         {
 181           PyErr_Restore (ptype, pvalue, ptraceback);
 182           gdbpy_print_stack ();
 183           if (msg != NULL && *msg != '\0')
 184             error (_("Error occurred in Python command: %s"), msg.get ());
 185           else
 186             error (_("Error occurred in Python command."));
 187         }
 188       else
 189         {
 190           Py_XDECREF (ptype);
 191           Py_XDECREF (pvalue);
 192           Py_XDECREF (ptraceback);
 193           error ("%s", msg.get ());
 194         }
 195     }
 196 }
 197
 198 /* Helper function for the Python command completers (both "pure"
 199    completer and brkchar handler).  This function takes COMMAND, TEXT
 200    and WORD and tries to call the Python method for completion with
 201    these arguments.
 202
 203    This function is usually called twice: once when we are figuring out
 204    the break characters to be used, and another to perform the real
 205    completion itself.  The reason for this two step dance is that we
 206    need to know the set of "brkchars" to use early on, before we
 207    actually try to perform the completion.  But if a Python command
 208    supplies a "complete" method then we have to call that method
 209    first: it may return as its result the kind of completion to
 210    perform and that will in turn specify which brkchars to use.  IOW,
 211    we need the result of the "complete" method before we actually
 212    perform the completion.  The only situation when this function is
 213    not called twice is when the user uses the "complete" command: in
 214    this scenario, there is no call to determine the "brkchars".
 215
 216    Ideally, it would be nice to cache the result of the first call (to
 217    determine the "brkchars") and return this value directly in the
 218    second call (to perform the actual completion).  However, due to
 219    the peculiarity of the "complete" command mentioned above, it is
 220    possible to put GDB in a bad state if you perform a TAB-completion
 221    and then a "complete"-completion sequentially.  Therefore, we just
 222    recalculate everything twice for TAB-completions.
 223
 224    This function returns the PyObject representing the Python method
 225    call.  */
 226
 227 static PyObject *
 228 cmdpy_completer_helper (struct cmd_list_element *command,
 229                         const char *text, const char *word)
 230 {
 231   cmdpy_object *obj = (cmdpy_object *) get_cmd_context (command);
 232
 233   if (obj == NULL)
 234     error (_("Invalid invocation of Python command object."));
 235   if (!PyObject_HasAttr ((PyObject *) obj, complete_cst))
 236     {
 237       /* If there is no complete method, don't error.  */
 238       return NULL;
 239     }
 240
 241   gdbpy_ref<> textobj (PyUnicode_Decode (text, strlen (text), host_charset (),
 242                                          NULL));
 243   if (textobj == NULL)
 244     error (_("Could not convert argument to Python string."));
 245   gdbpy_ref<> wordobj (PyUnicode_Decode (word, strlen (word), host_charset (),
 246                                          NULL));
 247   if (wordobj == NULL)
 248     error (_("Could not convert argument to Python string."));
 249
 250   gdbpy_ref<> resultobj (PyObject_CallMethodObjArgs ((PyObject *) obj,
 251                                                      complete_cst,
 252                                                      textobj.get (),
 253                                                      wordobj.get (), NULL));
 254   if (resultobj == NULL)
 255     {
 256       /* Just swallow errors here.  */
 257       PyErr_Clear ();
 258     }
 259
 260   return resultobj.release ();
 261 }
 262
 263 /* Python function called to determine the break characters of a
 264    certain completer.  We are only interested in knowing if the
 265    completer registered by the user will return one of the integer
 266    codes (see COMPLETER_* symbols).  */
 267
 268 static void
 269 cmdpy_completer_handle_brkchars (struct cmd_list_element *command,
 270                                  const char *text, const char *word)
 271 {
 272   gdbpy_enter enter_py (get_current_arch (), current_language);
 273
 274   /* Calling our helper to obtain the PyObject of the Python
 275      function.  */
 276   gdbpy_ref<> resultobj (cmdpy_completer_helper (command, text, word));
 277
 278   /* Check if there was an error.  */
 279   if (resultobj == NULL)
 280     return;
 281
 282   if (PyInt_Check (resultobj.get ()))
 283     {
 284       /* User code may also return one of the completion constants,
 285          thus requesting that sort of completion.  We are only
 286          interested in this kind of return.  */
 287       long value;
 288
 289       if (!gdb_py_int_as_long (resultobj.get (), &value))
 290         {
 291           /* Ignore.  */
 292           PyErr_Clear ();
 293         }
 294       else if (value >= 0 && value < (long) N_COMPLETERS)
 295         {
 296           /* This is the core of this function.  Depending on which
 297              completer type the Python function returns, we have to
 298              adjust the break characters accordingly.  */
 299           set_gdb_completion_word_break_characters
 300             (completers[value].completer);
 301         }
 302     }
 303 }
 304
 305 /* Called by gdb for command completion.  */
 306
 307 static VEC (char_ptr) *
 308 cmdpy_completer (struct cmd_list_element *command,
 309                  const char *text, const char *word)
 310 {
 311   VEC (char_ptr) *result = NULL;
 312
 313   gdbpy_enter enter_py (get_current_arch (), current_language);
 314
 315   /* Calling our helper to obtain the PyObject of the Python
 316      function.  */
 317   gdbpy_ref<> resultobj (cmdpy_completer_helper (command, text, word));
 318
 319   /* If the result object of calling the Python function is NULL, it
 320      means that there was an error.  In this case, just give up and
 321      return NULL.  */
 322   if (resultobj == NULL)
 323     return NULL;
 324
 325   result = NULL;
 326   if (PyInt_Check (resultobj.get ()))
 327     {
 328       /* User code may also return one of the completion constants,
 329          thus requesting that sort of completion.  */
 330       long value;
 331
 332       if (! gdb_py_int_as_long (resultobj.get (), &value))
 333         {
 334           /* Ignore.  */
 335           PyErr_Clear ();
 336         }
 337       else if (value >= 0 && value < (long) N_COMPLETERS)
 338         result = completers[value].completer (command, text, word);
 339     }
 340   else
 341     {
 342       gdbpy_ref<> iter (PyObject_GetIter (resultobj.get ()));
 343
 344       if (iter == NULL)
 345         return NULL;
 346
 347       while (true)
 348         {
 349           gdbpy_ref<> elt (PyIter_Next (iter.get ()));
 350           if (elt == NULL)
 351             break;
 352
 353           if (! gdbpy_is_string (elt.get ()))
 354             {
 355               /* Skip problem elements.  */
 356               continue;
 357             }
 358           gdb::unique_xmalloc_ptr<char>
 359             item (python_string_to_host_string (elt.get ()));
 360           if (item == NULL)
 361             {
 362               /* Skip problem elements.  */
 363               PyErr_Clear ();
 364               continue;
 365             }
 366           VEC_safe_push (char_ptr, result, item.release ());
 367         }
 368
 369       /* If we got some results, ignore problems.  Otherwise, report
 370          the problem.  */
 371       if (result != NULL && PyErr_Occurred ())
 372         PyErr_Clear ();
 373     }
 374
 375   return result;
 376 }
 377
 378 /* Helper for cmdpy_init which locates the command list to use and
 379    pulls out the command name.
 380
 381    NAME is the command name list.  The final word in the list is the
 382    name of the new command.  All earlier words must be existing prefix
 383    commands.
 384
 385    *BASE_LIST is set to the final prefix command's list of
 386    *sub-commands.
 387
 388    START_LIST is the list in which the search starts.
 389
 390    This function returns the xmalloc()d name of the new command.  On
 391    error sets the Python error and returns NULL.  */
 392
 393 char *
 394 gdbpy_parse_command_name (const char *name,
 395                           struct cmd_list_element ***base_list,
 396                           struct cmd_list_element **start_list)
 397 {
 398   struct cmd_list_element *elt;
 399   int len = strlen (name);
 400   int i, lastchar;
 401   char *prefix_text;
 402   const char *prefix_text2;
 403   char *result;
 404
 405   /* Skip trailing whitespace.  */
 406   for (i = len - 1; i >= 0 && (name[i] == ' ' || name[i] == '\t'); --i)
 407     ;
 408   if (i < 0)
 409     {
 410       PyErr_SetString (PyExc_RuntimeError, _("No command name found."));
 411       return NULL;
 412     }
 413   lastchar = i;
 414
 415   /* Find first character of the final word.  */
 416   for (; i > 0 && (isalnum (name[i - 1])
 417                    || name[i - 1] == '-'
 418                    || name[i - 1] == '_');
 419        --i)
 420     ;
 421   result = (char *) xmalloc (lastchar - i + 2);
 422   memcpy (result, &name[i], lastchar - i + 1);
 423   result[lastchar - i + 1] = '\0';
 424
 425   /* Skip whitespace again.  */
 426   for (--i; i >= 0 && (name[i] == ' ' || name[i] == '\t'); --i)
 427     ;
 428   if (i < 0)
 429     {
 430       *base_list = start_list;
 431       return result;
 432     }
 433
 434   prefix_text = (char *) xmalloc (i + 2);
 435   memcpy (prefix_text, name, i + 1);
 436   prefix_text[i + 1] = '\0';
 437
 438   prefix_text2 = prefix_text;
 439   elt = lookup_cmd_1 (&prefix_text2, *start_list, NULL, 1);
 440   if (elt == NULL || elt == CMD_LIST_AMBIGUOUS)
 441     {
 442       PyErr_Format (PyExc_RuntimeError, _("Could not find command prefix %s."),
 443                     prefix_text);
 444       xfree (prefix_text);
 445       xfree (result);
 446       return NULL;
 447     }
 448
 449   if (elt->prefixlist)
 450     {
 451       xfree (prefix_text);
 452       *base_list = elt->prefixlist;
 453       return result;
 454     }
 455
 456   PyErr_Format (PyExc_RuntimeError, _("'%s' is not a prefix command."),
 457                 prefix_text);
 458   xfree (prefix_text);
 459   xfree (result);
 460   return NULL;
 461 }
 462
 463 /* Object initializer; sets up gdb-side structures for command.
 464
 465    Use: __init__(NAME, COMMAND_CLASS [, COMPLETER_CLASS][, PREFIX]]).
 466
 467    NAME is the name of the command.  It may consist of multiple words,
 468    in which case the final word is the name of the new command, and
 469    earlier words must be prefix commands.
 470
 471    COMMAND_CLASS is the kind of command.  It should be one of the COMMAND_*
 472    constants defined in the gdb module.
 473
 474    COMPLETER_CLASS is the kind of completer.  If not given, the
 475    "complete" method will be used.  Otherwise, it should be one of the
 476    COMPLETE_* constants defined in the gdb module.
 477
 478    If PREFIX is True, then this command is a prefix command.
 479
 480    The documentation for the command is taken from the doc string for
 481    the python class.  */
 482
 483 static int
 484 cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
 485 {
 486   cmdpy_object *obj = (cmdpy_object *) self;
 487   const char *name;
 488   int cmdtype;
 489   int completetype = -1;
 490   char *docstring = NULL;
 491   struct cmd_list_element **cmd_list;
 492   char *cmd_name, *pfx_name;
 493   static const char *keywords[] = { "name", "command_class", "completer_class",
 494                                     "prefix", NULL };
 495   PyObject *is_prefix = NULL;
 496   int cmp;
 497
 498   if (obj->command)
 499     {
 500       /* Note: this is apparently not documented in Python.  We return
 501          0 for success, -1 for failure.  */
 502       PyErr_Format (PyExc_RuntimeError,
 503                     _("Command object already initialized."));
 504       return -1;
 505     }
 506
 507   if (!gdb_PyArg_ParseTupleAndKeywords (args, kw, "si|iO",
 508                                         keywords, &name, &cmdtype,
 509                                         &completetype, &is_prefix))
 510     return -1;
 511
 512   if (cmdtype != no_class && cmdtype != class_run
 513       && cmdtype != class_vars && cmdtype != class_stack
 514       && cmdtype != class_files && cmdtype != class_support
 515       && cmdtype != class_info && cmdtype != class_breakpoint
 516       && cmdtype != class_trace && cmdtype != class_obscure
 517       && cmdtype != class_maintenance && cmdtype != class_user)
 518     {
 519       PyErr_Format (PyExc_RuntimeError, _("Invalid command class argument."));
 520       return -1;
 521     }
 522
 523   if (completetype < -1 || completetype >= (int) N_COMPLETERS)
 524     {
 525       PyErr_Format (PyExc_RuntimeError,
 526                     _("Invalid completion type argument."));
 527       return -1;
 528     }
 529
 530   cmd_name = gdbpy_parse_command_name (name, &cmd_list, &cmdlist);
 531   if (! cmd_name)
 532     return -1;
 533
 534   pfx_name = NULL;
 535   if (is_prefix != NULL)
 536     {
 537       cmp = PyObject_IsTrue (is_prefix);
 538       if (cmp == 1)
 539         {
 540           int i, out;
 541
 542           /* Make a normalized form of the command name.  */
 543           pfx_name = (char *) xmalloc (strlen (name) + 2);
 544
 545           i = 0;
 546           out = 0;
 547           while (name[i])
 548             {
 549               /* Skip whitespace.  */
 550               while (name[i] == ' ' || name[i] == '\t')
 551                 ++i;
 552               /* Copy non-whitespace characters.  */
 553               while (name[i] && name[i] != ' ' && name[i] != '\t')
 554                 pfx_name[out++] = name[i++];
 555               /* Add a single space after each word -- including the final
 556                  word.  */
 557               pfx_name[out++] = ' ';
 558             }
 559           pfx_name[out] = '\0';
 560         }
 561       else if (cmp < 0)
 562         {
 563           xfree (cmd_name);
 564           return -1;
 565         }
 566     }
 567   if (PyObject_HasAttr (self, gdbpy_doc_cst))
 568     {
 569       gdbpy_ref<> ds_obj (PyObject_GetAttr (self, gdbpy_doc_cst));
 570
 571       if (ds_obj != NULL && gdbpy_is_string (ds_obj.get ()))
 572         {
 573           docstring = python_string_to_host_string (ds_obj.get ()).release ();
 574           if (docstring == NULL)
 575             {
 576               xfree (cmd_name);
 577               xfree (pfx_name);
 578               return -1;
 579             }
 580         }
 581     }
 582   if (! docstring)
 583     docstring = xstrdup (_("This command is not documented."));
 584
 585   Py_INCREF (self);
 586
 587   TRY
 588     {
 589       struct cmd_list_element *cmd;
 590
 591       if (pfx_name)
 592         {
 593           int allow_unknown;
 594
 595           /* If we have our own "invoke" method, then allow unknown
 596              sub-commands.  */
 597           allow_unknown = PyObject_HasAttr (self, invoke_cst);
 598           cmd = add_prefix_cmd (cmd_name, (enum command_class) cmdtype,
 599                                 NULL, docstring, &obj->sub_list,
 600                                 pfx_name, allow_unknown, cmd_list);
 601         }
 602       else
 603         cmd = add_cmd (cmd_name, (enum command_class) cmdtype, NULL,
 604                        docstring, cmd_list);
 605
 606       /* There appears to be no API to set this.  */
 607       cmd->func = cmdpy_function;
 608       cmd->destroyer = cmdpy_destroyer;
 609
 610       obj->command = cmd;
 611       set_cmd_context (cmd, self);
 612       set_cmd_completer (cmd, ((completetype == -1) ? cmdpy_completer
 613                                : completers[completetype].completer));
 614       if (completetype == -1)
 615         set_cmd_completer_handle_brkchars (cmd,
 616                                            cmdpy_completer_handle_brkchars);
 617     }
 618   CATCH (except, RETURN_MASK_ALL)
 619     {
 620       xfree (cmd_name);
 621       xfree (docstring);
 622       xfree (pfx_name);
 623       Py_DECREF (self);
 624       PyErr_Format (except.reason == RETURN_QUIT
 625                     ? PyExc_KeyboardInterrupt : PyExc_RuntimeError,
 626                     "%s", except.message);
 627       return -1;
 628     }
 629   END_CATCH
 630
 631   return 0;
 632 }
 633
 634 \f
 635
 636 /* Initialize the 'commands' code.  */
 637
 638 int
 639 gdbpy_initialize_commands (void)
 640 {
 641   int i;
 642
 643   cmdpy_object_type.tp_new = PyType_GenericNew;
 644   if (PyType_Ready (&cmdpy_object_type) < 0)
 645     return -1;
 646
 647   /* Note: alias and user are special; pseudo appears to be unused,
 648      and there is no reason to expose tui, I think.  */
 649   if (PyModule_AddIntConstant (gdb_module, "COMMAND_NONE", no_class) < 0
 650       || PyModule_AddIntConstant (gdb_module, "COMMAND_RUNNING", class_run) < 0
 651       || PyModule_AddIntConstant (gdb_module, "COMMAND_DATA", class_vars) < 0
 652       || PyModule_AddIntConstant (gdb_module, "COMMAND_STACK", class_stack) < 0
 653       || PyModule_AddIntConstant (gdb_module, "COMMAND_FILES", class_files) < 0
 654       || PyModule_AddIntConstant (gdb_module, "COMMAND_SUPPORT",
 655                                   class_support) < 0
 656       || PyModule_AddIntConstant (gdb_module, "COMMAND_STATUS", class_info) < 0
 657       || PyModule_AddIntConstant (gdb_module, "COMMAND_BREAKPOINTS",
 658                                   class_breakpoint) < 0
 659       || PyModule_AddIntConstant (gdb_module, "COMMAND_TRACEPOINTS",
 660                                   class_trace) < 0
 661       || PyModule_AddIntConstant (gdb_module, "COMMAND_OBSCURE",
 662                                   class_obscure) < 0
 663       || PyModule_AddIntConstant (gdb_module, "COMMAND_MAINTENANCE",
 664                                   class_maintenance) < 0
 665       || PyModule_AddIntConstant (gdb_module, "COMMAND_USER", class_user) < 0)
 666     return -1;
 667
 668   for (i = 0; i < N_COMPLETERS; ++i)
 669     {
 670       if (PyModule_AddIntConstant (gdb_module, completers[i].name, i) < 0)
 671         return -1;
 672     }
 673
 674   if (gdb_pymodule_addobject (gdb_module, "Command",
 675                               (PyObject *) &cmdpy_object_type) < 0)
 676     return -1;
 677
 678   invoke_cst = PyString_FromString ("invoke");
 679   if (invoke_cst == NULL)
 680     return -1;
 681   complete_cst = PyString_FromString ("complete");
 682   if (complete_cst == NULL)
 683     return -1;
 684
 685   return 0;
 686 }
 687
 688 \f
 689
 690 static PyMethodDef cmdpy_object_methods[] =
 691 {
 692   { "dont_repeat", cmdpy_dont_repeat, METH_NOARGS,
 693     "Prevent command repetition when user enters empty line." },
 694
 695   { 0 }
 696 };
 697
 698 PyTypeObject cmdpy_object_type =
 699 {
 700   PyVarObject_HEAD_INIT (NULL, 0)
 701   "gdb.Command",                  /*tp_name*/
 702   sizeof (cmdpy_object),          /*tp_basicsize*/
 703   0,                              /*tp_itemsize*/
 704   0,                              /*tp_dealloc*/
 705   0,                              /*tp_print*/
 706   0,                              /*tp_getattr*/
 707   0,                              /*tp_setattr*/
 708   0,                              /*tp_compare*/
 709   0,                              /*tp_repr*/
 710   0,                              /*tp_as_number*/
 711   0,                              /*tp_as_sequence*/
 712   0,                              /*tp_as_mapping*/
 713   0,                              /*tp_hash */
 714   0,                              /*tp_call*/
 715   0,                              /*tp_str*/
 716   0,                              /*tp_getattro*/
 717   0,                              /*tp_setattro*/
 718   0,                              /*tp_as_buffer*/
 719   Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
 720   "GDB command object",           /* tp_doc */
 721   0,                              /* tp_traverse */
 722   0,                              /* tp_clear */
 723   0,                              /* tp_richcompare */
 724   0,                              /* tp_weaklistoffset */
 725   0,                              /* tp_iter */
 726   0,                              /* tp_iternext */
 727   cmdpy_object_methods,           /* tp_methods */
 728   0,                              /* tp_members */
 729   0,                              /* tp_getset */
 730   0,                              /* tp_base */
 731   0,                              /* tp_dict */
 732   0,                              /* tp_descr_get */
 733   0,                              /* tp_descr_set */
 734   0,                              /* tp_dictoffset */
 735   cmdpy_init,                     /* tp_init */
 736   0,                              /* tp_alloc */
 737 };
 738
 739 \f
 740
 741 /* Utility to build a buildargv-like result from ARGS.
 742    This intentionally parses arguments the way libiberty/argv.c:buildargv
 743    does.  It splits up arguments in a reasonable way, and we want a standard
 744    way of parsing arguments.  Several gdb commands use buildargv to parse their
 745    arguments.  Plus we want to be able to write compatible python
 746    implementations of gdb commands.  */
 747
 748 PyObject *
 749 gdbpy_string_to_argv (PyObject *self, PyObject *args)
 750 {
 751   const char *input;
 752
 753   if (!PyArg_ParseTuple (args, "s", &input))
 754     return NULL;
 755
 756   gdbpy_ref<> py_argv (PyList_New (0));
 757   if (py_argv == NULL)
 758     return NULL;
 759
 760   /* buildargv uses NULL to represent an empty argument list, but we can't use
 761      that in Python.  Instead, if ARGS is "" then return an empty list.
 762      This undoes the NULL -> "" conversion that cmdpy_function does.  */
 763
 764   if (*input != '\0')
 765     {
 766       char **c_argv = gdb_buildargv (input);
 767       int i;
 768
 769       for (i = 0; c_argv[i] != NULL; ++i)
 770         {
 771           gdbpy_ref<> argp (PyString_FromString (c_argv[i]));
 772
 773           if (argp == NULL
 774               || PyList_Append (py_argv.get (), argp.get ()) < 0)
 775             {
 776               freeargv (c_argv);
 777               return NULL;
 778             }
 779         }
 780
 781       freeargv (c_argv);
 782     }
 783
 784   return py_argv.release ();
 785 }